Replaceable upper chamber parts of plasma processing apparatus

ABSTRACT

An upper chamber section of a plasma reaction chamber includes a ceramic window with blind bores in an upper surface for receipt of a thermal couple and a resistance temperature detector, a top chamber interface which comprises an upper surface which vacuum seals against the bottom of the window and a gas injection system comprising 8 side injectors mounted in the sidewall of the top chamber interface and a gas delivery system comprising tubing which provides symmetric gas flow to the 8 injectors from a single gas feed connection.

This application claims priority under 35 U.S.C. §119 to U.S.provisional application No. 61/241,321 entitled REPLACEABLE UPPERCHAMBER PARTS OF PLASMA PROCESSING APPARATUS, filed Sep. 10, 2009, theentire content of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates in general to semiconductor substratemanufacturing technologies and in particular to a replacement parts ofan upper chamber section of a plasma chamber.

BACKGROUND OF THE INVENTION

In the processing of a substrate, e.g., a semiconductor substrate or aglass panel such as one used in flat panel display manufacturing, plasmais often employed. As part of the processing of a substrate for example,the substrate is divided into a plurality of dies, or rectangular areas,each of which will become an integrated circuit. The substrate is thenprocessed in a series of steps in which materials are selectivelyremoved (etching) and deposited (deposition) in order to form electricalcomponents thereon.

In an exemplary plasma process, a substrate is coated with a thin filmof hardened emulsion (i.e., such as a photoresist mask) prior toetching. Areas of the hardened emulsion are then selectively removed,causing components of the underlying layer to become exposed. Thesubstrate is then placed in a plasma processing chamber on a substratesupport structure comprising a mono-polar or bi-polar electrode, calleda chuck or pedestal. Appropriate etchant source are then flowed into thechamber and struck to form a plasma to etch exposed areas of thesubstrate.

Referring now to FIG. 1, a simplified diagram of inductively coupledplasma processing system components is shown. Generally, the plasmachamber (chamber) 202 is comprised of a bottom chamber section 250forming a sidewall of the chamber, an upper chamber section 244 alsoforming a sidewall of the chamber, and a cover 252. An appropriate setof gases is flowed into chamber 202 from gas distribution system 222.These plasma processing gases may be subsequently ionized to form aplasma 220, in order to process (e.g., etch or deposition) exposed areasof substrate 224, such as a semiconductor substrate or a glass pane,positioned with edge ring 215 on an electrostatic chuck (chuck) 216. Gasdistribution system 222 is commonly comprised of compressed gascylinders (not shown) containing plasma processing gases (e.g., C₄F₈,C₄F₆, CHF₃, CH₂F₃, CF₄, HBr, CH₃F, C₂F₄, N₂, O₂, Ar, Xe, He, H₂, NH₃,SF₆, BCl₃, Cl₂, etc.).

Induction coil 231 is separated from the plasma by a dielectric window204 forming the upper wall of the chamber, and generally induces atime-varying electric current in the plasma processing gases to createplasma 220. The window both protects induction coil from plasma 220, andallows the generated RF field 208 to generate an inductive current 211within the plasma processing chamber. Further coupled to induction coil231 is matching network 232 that may be further coupled to RF generator234. Matching network 232 attempts to match the impedance of RFgenerator 234, which typically operates at about 13.56 MHz and about 50ohms, to that of the plasma 220. Additionally, a second RF energy source238 may also be coupled through matching network 236 to the substrate224 in order to create a bias with the plasma, and direct the plasmaaway from structures within the plasma processing system and toward thesubstrate. Gases and byproducts are removed from the chamber by a pump220.

Generally, some type of cooling system 240 is coupled to chuck 216 inorder to achieve thermal equilibrium once the plasma is ignited. Thecooling system itself is usually comprised of a chiller that pumps acoolant through cavities within the chuck, and helium gas pumped betweenthe chuck and the substrate. In addition to removing the generated heat,the helium gas also allows the cooling system to rapidly control heatdissipation. That is, increasing helium pressure increases the heattransfer rate. Most plasma processing systems are also controlled bysophisticated computers comprising operating software programs. In atypical operating environment, manufacturing process parameters (e.g.,voltage, gas flow mix, gas flow rate, pressure, etc.) are generallyconfigured for a particular plasma processing system and a specificrecipe.

In addition, a heating and cooling apparatus 246 may operate to controlthe temperature of the upper chamber section 244 of the plasmaprocessing apparatus 202 such that the inner surface of the upperchamber section 244, which is exposed to the plasma during operation, ismaintained at a controlled temperature. The heating and coolingapparatus 246 is formed by several different layers of material toprovide both heating and cooling operations.

The upper chamber section itself is commonly constructed from plasmaresistant materials that either will ground or are transparent to thegenerated RF field within the plasma processing system (e.g., coated oruncoated aluminum, ceramic, etc.).

For example, the upper chamber section can be a machined piece ofaluminum which can be removed for cleaning or replacement thereof. Theinner surface of the upper chamber section is preferably coated with aplasma resistant material such as a thermally sprayed yttria coating.Cleaning is problematic in that the ceramic coatings of this type areeasily damaged and due to the sensitive processing of some plasmaprocesses, it is sometimes preferred to replace the upper chambersection rather than remove it for cleaning.

In addition, correctly reseating the upper chamber section aftermaintenance is often difficult, since it must properly be aligned withthe bottom chamber section such that a set of gaskets properly sealaround the upper chamber section. A slight misalignment will preclude aproper mounting arrangement.

The volume of material in the upper chamber section also tends to add asubstantial thermal mass to the plasma processing system. Thermal massrefers to materials have the capacity to store thermal energy forextended periods. In general, plasma processes tend to very sensitive totemperature variation. For example, a temperature variation outside theestablished process window can directly affect the etch rate or thedeposition rate of polymeric films, such as poly-fluorocarbon, on thesubstrate surface. Temperature repeatability between substrates is oftendesired, since many plasma processing recipes may also requiretemperature variation to be on the order of a few tenths of degree C.Because of this, the upper chamber section is often heated or cooled inorder to substantially maintain the plasma process within establishedparameters.

As the plasma is ignited, the substrate absorbs thermal energy, which issubsequently measured and then removed through the cooling system.Likewise, the upper chamber section can be thermally controlled.However, plasma processing may require temperature changes duringmulti-step processing and it may be necessary to heat the upper chambersection to temperatures above 100° C., e.g. 120, 130, 140, 150 or 160°C. or any temperature therebetween whereas the prior upper chambersections were run at much lower temperatures on the order of 60° C. Thehigher temperatures can cause undesirable increases in temperature ofadjacent components such as the bottom chamber section. For example, ifit is desired to run the upper chamber section and overlying dielectricwindow at temperatures on the order of 130 to 150° C. and the bottomchamber section at ambient temperatures of about 30° C., heat from themuch hotter upper chamber section can flow into the bottom chambersection and raise its temperature sufficiently to affect the plasmaprocessing conditions seen by the semiconductor substrate. Thus, heatflow variations originating from the upper chamber section may cause thesubstrate temperature to vary outside narrow recipe parameters.

In view of the foregoing, replaceable upper chamber parts having desiredfeatures which cooperate to optimize plasma processing in a plasmaprocessing system would be of interest.

SUMMARY OF THE INVENTION

In a preferred embodiment, a replaceable top chamber interface of anupper chamber section of a plasma reaction chamber in whichsemiconductor substrates can be processed, comprises a monolithic metalcylinder having a uniform diameter inner surface, an upper vacuumsealing surface extending horizontally away from the inner surface and alower vacuum sealing surface extending horizontally away from the innersurface; the upper annular vacuum sealing surface adapted to sealagainst a dielectric window of the plasma chamber; the lower annularvacuum sealing surface adapted to seal against a bottom section of theplasma chamber; a thermal mass at an upper portion of the cylinder, thethermal mass defined by a wider portion of the cylinder between theinner surface and an outer surface extending vertically from the upperflange, the thermal mass being effective to provide azimuthaltemperature uniformity of the inner surface, and a thermal choke at alower portion of the cylinder effective to minimize transfer of heatacross the lower vacuum sealing surface, the thermal choke defined by athin metal section having a thickness of less than 0.25 inch andextending at least 25% of the length of the inner surface.

In another embodiment, a replaceable window of an upper chamber sectionof a plasma reaction chamber in which semiconductor substrates can beprocessed, comprises a ceramic disk having a uniform thickness, at leastone blind hole configured to receive a temperature monitoring sensor, avacuum sealing surface adapted to seal against an upper vacuum sealingsurface of a top chamber interface, and a central bore configured toreceive a top gas injector which delivers process gas into the center ofthe chamber.

In a further embodiment, a gas delivery system configured to supply gasto side injectors mounted in a sidewall of the top chamber interfacecomprises bifurcated gas lines which receive tuning gas from a commonfeed and gas tubes arranged to flow the tuning gas equal distances fromthe common feed to the injectors. The side injectors can include 8injectors symmetrically arranged around the top chamber interface andthe gas lines can include eight gas lines of which two primary gas linesof equal length extend from the common feed, two secondary gas lines ofequal length extend from the outlets of the primary gas lines and fourtertiary gas lines of equal length extend from outlets of the secondarygas lines. The primary gas lines are longer than the secondary gas linesand the secondary gas lines are longer than the tertiary gas lines. Theprimary gas lines are connected to midpoints of the secondary gas linesand the secondary gas lines are connected to midpoints of the tertiarygas lines. The gas delivery system is designed to fit within a smallvolume defined by an annular recess in the outer surface of the topchamber interface.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 shows a simplified diagram of a plasma processing system;

FIG. 2 shows a perspective view of an exemplary plasma chamber which caninclude a window, a top chamber interface and a side injector gas supplysystem as described herein.

FIGS. 3A-D show details of a top chamber interface as described herein.

FIGS. 4A-H show details of a ceramic window described herein.

FIGS. 5A-K show details of a side gas injection delivery systemdescribed herein.

FIGS. 6A-B show details of a gas injector which mounts in an opening inthe sidewall of the top chamber interface and is supplied gas by theside gas injection system.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in detail with reference toa few preferred embodiments thereof as illustrated in the accompanyingdrawings. In the following description, numerous specific details areset forth in order to provide a thorough understanding of the presentinvention. It will be apparent, however, to one skilled in the art, thatthe present invention may be practiced without some or all of thesespecific details. In other instances, well known process steps and/orstructures have not been described in detail in order to notunnecessarily obscure the present invention. As used herein, the term“about” should be construed to include values up to 10% above or belowthe values recited.

Described herein are replaceable parts of an upper chamber section of aplasma chamber such as that illustrated in FIG. 2. The parts include aceramic window, top chamber interface and side gas injection deliverysystem.

The plasma system shown in FIG. 2 includes a chamber 10 which includes alower chamber 12 and an upper chamber 14. The upper chamber 14 includesa top chamber interface 15 which supports a dielectric window 16. An RFcoil 18 overlies the window and supplies RF power for energizing processgas into a plasma state inside the chamber. A top gas injector ismounted in the center of the window for delivering process gas from gassupply line 20.

FIGS. 3A-D show details of the top chamber interface 15. FIG. 3A is atop view of the top chamber interface 15, FIG. 3B is a side crosssectional view illustrating a thickened wall section 15 a, a thin walledsection 15 b, an upper vacuum sealing surface 15 c, a lower vacuumsealing surface 15 d and side injection ports 15 e in side wall 15 f.FIG. 3C shows details of the upper vacuum sealing surface 15 c whereinvarious dimensions of the surface and of a groove 15 g for receipt of anO-ring are set forth. FIG. 3D is a perspective view showing locations ofthe side gas injectors in an annular recess 15 h in the outer wall 15 i.

FIG. 4A shows details of the window 16 which includes a central opening16 a for receipt of a top injector, blind holes 16 b in upper surface 16c for receipt of temperature sensors, and a clocking feature 16 d in abottom flange 16 e of the outer side surface 16 f. FIG. 4B is a sideview of the window shown in FIG. 4A. FIG. 4C shows details of a vacuumsealing surface 16 g which is outward of a recessed surface which iscoated with a ceramic coating such as plasma sprayed yttrium oxide. FIG.4D is a cross section of the outer periphery of the window wherein arounded recess 16 i extends into the sidewall 16 f. FIG. 4E showsdetails and dimensions of one of the blind bores 16 b. FIG. 4F showsdetails and dimensions of the clocking feature 16 d which is a recesshaving a radius of 0.625 inch extending into the side of the window at asingle location and edges of the recess form an angle of 90° with thecenter of the radius. FIG. 4G shows details and dimensions of the windowand FIG. 4H shows a cross section of the window illustrating therelative depths of the blind bores.

FIG. 5A shows a top view of the chamber wherein the cylindrical topchamber interface 15 is located within a square housing of the upperchamber 14. FIG. 5B is an enlargement of the upper left corner in FIG.5A illustrating a bracket arrangement for supporting the top chamberinterface. FIG. 5C illustrates a side injection gas supply system 50which includes a common gas supply feed 50 a, two equal length primarygas lines 50 b, two equal length secondary gas lines 50 c, four equallength tertiary gas lines 50 d and eight connections 50 e which delivertuning gas to eight side injector locations. FIG. 5D shows how the gasinjection system 50 (wherein tuning gas travels the same distance fromthe common feed 50 a to each of the side injectors) fits within a smallvolume defined by the annular recess in the outer surface of the topchamber interface 15. FIG. 5E shows details of the common gas feed 50 aand the two primary gas lines 50 b which terminate in a connection 50 f.FIG. 5F shows details of one of the secondary gas lines 50 c bifurcatedby gas connection 50 g (which connects to gas connection 50 f) and twotertiary gas lines 50 d bifurcated by connections 50 h which connect toends of the secondary gas lines 50 c. FIG. 5G shows details of a sidegas injector 50 i mounted in the sidewall of the top chamber interface15. FIG. 5H shows details of how the primary gas line 50 b fits withinthe annular recess in the sidewall of the top chamber interface 15. FIG.5I shows details of how the gas injection system delivers gas to one ofthe side injectors 50 i. FIG. 5J shows a side gas injector 50 i and FIG.5K shows a washer 50 j which fits between a surface of a side gasinjector 50 i and an opposed surface in a side injection port 15 e ofthe top chamber interface 15.

In a preferred embodiment, the top chamber interface is a hard anodizedaluminum cylinder that has features for mounting process supporthardware (RF input coil, temperature controlled window, alignmentfeatures, chamber temperature control hardware, side gas injectors, gasdelivery tubing, etc.), sealing vacuum, and conducting electricalcurrent out of the part. The vacuum seals are preferably one or moreO-rings at the top and bottom of the cylinder. Electrical conduction ispreferably established through the use of a metallic spring RF gasketthat fits into a groove on the cylinder and contacts a bare metal stripon an adjacent component. The weight and thermal mass are increased atthe upper portion of the cylinder to achieve the desired temperatureuniformity. The internal plasma exposed surface can be coated with aceramic material such as plasma sprayed yttrium oxide.

FIG. 6A shows an end view of the proximal end of one of the eight sidegas injectors 50 i and FIG. 6B shows a cross section of the injector 50i taken along lines A-A in FIG. 6A. The injector 50 i includes aninjector body 60 which has a central bore 61 of uniform diameter of0.038 to 0.042 inch, preferably 0.040 inch extending axially throughproximal and distal end surfaces of the injector body 60. The injectorbody 60 has a total length of 0.52 to 0.53, preferably 0.526 inch, anouter diameter of 0.2 to 0.3, preferably 0.25 inch at an upstreamsection 62 which extends 0.275 to 0.285, preferably 0.278 inch and anouter diameter of 0.12 to 0.13, preferably 0.125 inch at the downstreamsection 63 having a length of 0.245 to 0.250, preferably 0.248 inch. Thecentral bore has an aspect ratio of at least 10, preferably 13 to 14.This aspect ratio of the bore can control back diffusion into theinjector to prevent corrosion of the stainless steel gas feed lines. Thedistal end 64 of the downstream end 63 includes a 45° (±10° chamferforming a 0.005 to 0.015, preferably 0.01 inch wide annular surface 65.The corner 66 between the outer surface of downstream section 63 andsurface 67 which is perpendicular to and extends between the outersurfaces of the upstream and downstream sections is rounded with aradius of 0.005 to 0.015, preferably 0.01 inch. The surface 67 bearsagainst washer 50 j as shown in FIG. 5K. The proximal end surface 68 ofthe upstream section 62 bears against another washer which surrounds anoutlet of the connection 50 e as shown in FIG. 5I. As can be seen inFIG. 5I, the distal end of the injector 50 i projects beyond the sidewall. Preferably the distal end of the injector 50 i extends 0.05 to0.2, more preferably about 0.1 inch into the chamber.

In accordance with a preferred embodiment, the window is a ceramic diskwith a bore in the middle that interfaces with a ceramic gas injector.It also has a raised landing pad of about 0.008 inch which extends about0.5 inch from the outer periphery on the bottom outer diameter (OD) thatinterfaces with the top chamber interface. There is an O-ring seal atthe interface between the window and the top chamber interface. Theceramic disk is about 1 inch thick and is made from a low loss tangenthigh purity ceramic material such as alumina and is coated on the bottomrecessed surface with yttrium oxide for plasma resistance. The disk hastwo blind bores on the top surface that accept a thermal couple (TC) anda Resistance Temperature Detector (RTD). The location and depth of theTC and RTD are selected to achieve desired process temperaturemonitoring and avoid damage to the window. The bottom of the TC and RTDholes have a spherical radius to reduce the stress concentration of thehole.

The contact area between the top chamber interface and the windowdetermines the amount of heat transferred between these two components.During plasma processing, the middle of the window is hot, and it isdesirable for the contact area to conduct heat into the edge of thewindow to help make the temperature of the OD close to that of themiddle. At idle (when plasma is not generated in the chamber), themiddle of the window is cold, and it is desirable for the contact areato not conduct any heat into the window and to match the temperature ofthe middle of the window.

The depth of the TC and RTD is established by determining where theneutral axis (zero stress line, it is the line that separates thetensile and compressive stresses) of the window is, and keeping thebottom of the hole above that axis. The analysis can also determine whatthe temperature difference is at the measured point, and the point ofinterest. This difference can be accounted for in software used toconduct the analysis.

The location of the TC and RTD is also analyzed to determine what offsetneeds to be accounted for in the software. The stress in the window canbe correlated to the temperature difference between the middle and OD ofthe window. This analysis can correlate the temperature of the middle ofthe window and the temperature of the measured point since thetemperature of the middle of the window cannot be measured due to thepresence of the top gas injector.

If the bottom of the holes do not have the spherical radius, the windowwould have a high stress concentration where the holes are located.Because the inside of the window is subject to the vacuum pressure inthe chamber, the window could fracture when there is a thermal gradientfrom the center to the edge of the window if the bottoms of the holesare not rounded. Adding a spherical radius at the bottom of the holeseliminates sharp edges and therefore reduces the stress and likelihoodof fracture.

The ceramic window can be replaced, serviced, maintained and is easilymanufacturable. The window is preferably about 1 inch thick and about 22inches in diameter. The desired dimensions of the bores for the TC andRTD are 0.494±0.009 inch from the yttrium coated surface and the boresare 180° apart on a radius of about 5.6 inches from the center of thewindow. The bores have a total depth of about 0.5 inch and the entrancesof the bores 16 b are tapered at 45° with a diameter of 0.390 inch atthe bore entrance. The bottoms of the bores have a diameter of about0.130 inch.

The side injection system can deliver a tuning gas and the system isdesigned to be a removable, serviceable, maintainable, manufacturable,leak resistant, plasma resistant, symmetrically fed 8 port gas injectionsystem. It can operate within a temperature range of 20° C.-120° C. anduses ¼ inch stainless steel tubing and custom designed, low-profilevacuum sealing interfaces. Nearly every surface in the side gasinjection system fits within a space of rectangular cross section 0.750inch wide by 1.612 inches tall and, simultaneously, nearly every surfacedoes not extend outside a diameter of 22.5 inches.

The function of the side gas injection system is to provide tuning gasuniformly into the plasma. The flow rate and flow uniformity of the sidegas injection system are primarily the functions of the inner borediameter of the eight side gas injectors which are made of solid yttria,total volume of the gas delivery tubes, and symmetric path to allinjector locations from the singular gas feed location. Dimensions ofthe gas injection system can be: inner bore diameter of each solidyttria injector: 0.040±0.002 inch, volume of gas injection system fromVCR fitting (the gas fitting at the upstream end of common feed 50 a):2.922 in³, gas travel path length to each injector from VCR fitting:37.426 inches.

The vacuum fitting interfaces are smaller than, for example, a K1Sfitting and the yttria side gas injector, which is the only piece of thesystem directly exposed to plasma, can be minimized in size and replacedwhen consumed without having to replace the much more expensivestainless steel weldments.

The top chamber interface is an anodized and ceramic-coated aluminumcylinder with O-ring seals on top and bottom and a top contact surfacemating with the ceramic window. The top chamber is actively heated andmaintained at a constant temperature for repeatable wafer processing.

The temperature at the edge of the window is largely controlled by theinterface to the top chamber. The chamber interface largely controls howmuch heat goes into or is removed from the edge of the window. Thus inorder to keep the edge cool during idle and hot during wafer processingit is desirable to keep temperature gradients small during idle orprocessing so that an optimum heat flow across the interface isprovided. Too much heat flow during idle will cause the edge to get toohot and fracture the window. Too little heat flow during waferprocessing will cause the edge to be too cold, and lead to fracture. Thefeature of the interface which largely controls the heat flow across theinterface is the contact surface area of the chamber to the window inair. The in-air contact region is from the outer diameter of the O-ringgroove to the outer diameter of the chamber where the window contactsthe chamber. These dimensions can be optimized by analysis and testingfor the heat flow during idle and during wafer processing.

In addition, the flatness of the interface is critical to the heattransfer and must be maintained. Various desired dimensions includeouter O-ring groove diameter Ø1=21.290±0.007 inch, chamber contactregion outer diameter Ø2=22.00±0.005 inch, chamber contact regionflatness 0.002 inch.

Having disclosed exemplary embodiments and the best mode, modificationsand variations may be made to the disclosed embodiments while remainingwithin the subject and spirit of the invention as defined by thefollowing claims.

What is claimed is:
 1. A replaceable upper chamber part of a plasmareaction chamber in which semiconductor substrates can be processed, thechamber part comprising: a removable gas delivery system received in anannular recess in an outer surface of a top chamber interface, theremovable gas delivery system comprises bifurcated gas lines whichreceive tuning gas from a common feed and gas tubes arranged to flow thetuning gas equal distances from the common feed to injectors mounted ina side wall of the top chamber interface.
 2. The replaceable upperchamber part of claim 1, wherein the gas delivery system includes eightinjectors symmetrically arranged around the top chamber interface andthe gas lines include eight gas lines of which two primary gas lines ofequal length extend from the common feed, two secondary gas lines ofequal length extend from the outlets of the primary gas lines and fourtertiary gas lines of equal length extend from outlets of the secondarygas lines.
 3. The replaceable upper chamber part of claim 2, wherein theprimary gas lines are longer than the secondary gas lines and thesecondary gas lines are longer than the tertiary gas lines, the primarygas lines are connected to midpoints of the secondary gas lines and thesecondary gas lines are connected to midpoints of the tertiary gaslines.
 4. The replaceable upper chamber part of claim 1, wherein the gasdelivery system is designed to fit within a small volume defined by theannular recess in the outer surface of the top chamber interface.
 5. Thereplaceable upper chamber part of claim 1, wherein the gas tubes arestainless steel.
 6. The replaceable upper chamber part of claim 1,wherein the removable gas delivery system operates within a temperaturerange of about 20° C. to about 120° C.
 7. The replaceable upper chamberpart of claim 1, the top chamber interface comprising a monolithic metalcylinder having a uniform diameter inner surface, an upper flangeextending horizontally away from the inner surface and a lower flangeextending horizontally away from the inner surface, an upper annularvacuum sealing surface; a lower annular vacuum sealing surface, athermal mass at an upper portion of the cylinder, the thermal massdefined by a wider portion of the cylinder between the inner surface andan outer surface extending vertically from the upper flange, the thermalmass being effective to provide azimuthal temperature uniformity of theinner surface, and a thermal choke at a lower portion of the cylindereffective to minimize transfer of heat across the lower vacuum sealingsurface, the thermal choke defined by a thin metal section having athickness of less than 0.25 inch and extending at least 25% of thelength of the inner surface.
 8. The replaceable upper chamber part ofclaim 7, wherein the outer surface of the top chamber interface includesthe annular recess and the gas delivery system is fitted completelywithin a volume defined by the annular recess.
 9. The replaceable upperchamber part of claim 7, wherein the top chamber interface is anodizedaluminum.
 10. The replaceable upper chamber part of claim 7, incombination with a window comprising a ceramic disk having a uniformthickness, at least one blind hole configured to receive a temperaturemonitoring sensor, a vacuum sealing surface sealed against an upperflange of the top chamber interface, and a central bore configured toreceive a top gas injector which delivers process gas into the center ofthe chamber.
 11. The replaceable upper chamber part of claim 10, whereinthe window includes two blind bores in the upper surface, the boresconfigured to mount temperature sensing probes therein.
 12. Thereplaceable upper chamber part of claim 10, wherein the window includesa central opening, the opening configured to provide a lockingengagement with a cylindrical gas injector body having a central gaspassage which delivers process gas to an open space in the chamberbeneath the window.
 13. The replaceable upper chamber part of claim 10,wherein the top chamber interface includes a groove in the upper flangeconfigured to receive an O-ring which provides a vacuum seal between thewindow and the top chamber interface.
 14. The replaceable upper chamberpart of claim 10, wherein the window includes a thermally sprayed yttriacoating on a lower surface thereof.
 15. A replaceable upper chamber partof a plasma reaction chamber in which semiconductor substrates can beprocessed, the chamber part comprising: a top chamber interface, the topchamber interface comprises a monolithic metal cylinder having a uniformdiameter inner surface, an upper flange extending horizontally away fromthe inner surface and a lower flange extending horizontally away fromthe inner surface, an upper annular vacuum sealing surface; a lowerannular vacuum sealing surface, a thermal mass at an upper portion ofthe cylinder, the thermal mass defined by a wider portion of thecylinder between the inner surface and an outer surface extendingvertically from the upper flange, the thermal mass being effective toprovide azimuthal temperature uniformity of the inner surface, and athermal choke at a lower portion of the cylinder effective to minimizetransfer of heat across the lower vacuum sealing surface, the thermalchoke defined by a thin metal section having a thickness of less than0.25 inch and extending at least 25% of the length of the inner surface,and an annular recess in the outer surface of the top chamber interface,and a plurality of symmetrically arranged side injection ports locatedin the inner surface.
 16. The replaceable upper chamber part of claim15, in combination with a window comprising a ceramic disk having auniform thickness, at least one blind hole configured to receive atemperature monitoring sensor, a vacuum sealing surface sealed againstthe upper flange, and a central bore configured to receive a top gasinjector which delivers process gas into the center of the chamber. 17.The replaceable upper chamber part of claim 16, wherein the top chamberinterface includes a groove in the upper flange configured to receive anO-ring, which provides a vacuum seal between the window and the topchamber interface.
 18. The replaceable upper chamber part of claim 16,wherein the window includes two blind bores in the upper surface, thebores configured to mount temperature sensing probes therein.
 19. Thereplaceable upper chamber part of claim 16, wherein the window includesa central opening, the opening configured to provide a lockingengagement with a cylindrical gas injector body having a central gaspassage which delivers process gas to an open space in the chamberbeneath the window, and a thermally sprayed yttria coating on a lowersurface thereof.
 20. The replaceable upper chamber part of claim 15,wherein the top chamber interface is anodized aluminum.